4D printing is cooler than 3D printing, and why that means the end of IKEA flatpacks

Just as you got used to the idea that toys, homewares, even guns can be built with 3D printers, the next phase is upon us. Researchers, including Australians, are already building objects with 4D printing, where time becomes the fourth dimension.

"4D printing is in essence 3D printed structures that can change their shape over time," said inventor and engineer Marc in het Panhuis​. "They're like transformers," he says.

And their applications will be limitless. Imagine medical devices that can transform their shape inside the body, water pipes that expand or contract depending on water demand and self-assembling furniture.

Professor in het Panhuis' team at the ARC Centre of Excellence for Electromaterials Science, located at the University of Wollongong, have just built an autonomous valve that opens in warm water and closes in cold water.

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The valve is made out of four types of hard or soft hydrogels - networks of polymers - fabricated at the same time using a 3D printer.

Inside the valve's structure a series of actuators respond to hot or cold water to open and close the valve.

While the valve's shape change is activated by water, other 4D printed devices transform by shaking, magnets or changes in temperature.

"It's a widely expanding field," Professor in het Panhuis said.

"You can buy jewellery that's 3D printed and changes shape when you put it on," he said.

US inventor Skylar Tibbits, who runs MIT's Self-Assembly Lab and coined the term 4D printing, is exploring 4D printing to manufacture furniture that can build itself.

"Rather than receiving a flat-pack and getting your screwdriver out, what he's postulating is what if you just add a bit of water to it and it assembles itself," Professor in het Panhuis said.

While its early days, the group are more advanced in their

The military is another industry interested in objects that can change shape or self destruct, Mission Impossible style.

"When armies are on the battlefield they leave a lot of electronics behind. What if you could make 3D printed electronics that [once the soldiers leave] undergo transient behaviour once they become too hot, or too cold, or too wet so they completely disappear so the enemy can't use any of your materials," Professor in het Panhuis said.

In 2012 DARPA researchers created implantable medical device that could deliver anti-microbial treatment to a wound site but would dissolve when no longer needed.

The electronic devices were made of ultra-thin silicon, magnesium and silk that could dissolve in the body, reducing the risk of a secondary site infection.